<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta charset="UTF-8"><!--申明当前网页的编码集UTF-8-->
    <meta name="Generator" content="EditPlus®">   <!--编辑器的名称-->
    <meta name="Author" content="作者是谁">
    <meta name="Keywords" content="关键词">
    <meta name="Description" content="描述和简介">
    <style type="text/css">
        body, dl, dd, dt, p, h1, h2, h3, h4, h5, h6 {
            margin: 0;
        }

        ul, ol {
            margin: 0;
            list-style: none;
            padding: 0;
        }

        a {
            text-decoration: none;
        }

        * {
            margin: 0;
            padding: 0;
        }

        .main {
            width: 1200px;
            margin: 20px auto
        }

        .main div {
            width: 200px;
            margin: auto;
            box-shadow: 0 0 10px 0 #00dd00
        }

        .main div p {
            width: 40px;
            height: 40px;
            box-shadow: 0 0 10px 0 #000;
            margin: auto;
            text-align: center;
            line-height: 40px
        }

        .main .box1 p:not(.box1_p) {
            background: red
        }

        .main .box1 p:not(#box1_p) {
            background: deeppink
        }

        .main .box2 p:empty {
            background: greenyellow
        }

        .main .box3 p:target {
            background: blue
        }

        .main .box4 span::selection {
            background: deeppink
        }
    </style>
</head>
<body>
<div class="main">
    <div class="box1">
        <p class="box1_p">1_1</p>
        <p>1_2</p>
        <p id="box1_p">1_3</p>
        <p>1_4</p>
    </div>
    <div class="box2">
        <p>2_1</p>
        <p>2_2</p>
        <p></p>
        <p>2_4</p>
    </div>
    <div class="box3">
        <p><a href="#box3_p3_2">点击</a></p>
        <p id="box3_p3_2">3_2</p>
        <p><a href="#box3_p3_4">点击</a></p>
        <p id="box3_p3_4">3_4</p>
    </div>
    <div class="box4">
        <span>不积跬步无以至千里，不积小流无以成江河。山外青山楼外楼，没有比脚更远的路，没有比人更高的山</span>
    </div>
</div>
</body>
</html>